Vibrational Raman and infrared spectroscopy are used to probe the dynamical, conformational, functional and thermodynamic properties of both model and intact membrane assemblies. Emphasis is placed on elucidating both lipid-lipid and lipid-protein interactions within the membrane bilayer complex. For example, the association between ferricytochrome c, a mobile electron- transfer protein which diffuses between the inner and outer mitochondrial membranes, and cardiolipin was studied using resonance Raman spectroscopic techniques. The observed data exhibit the accepted spectral frequency and intensity markers for ferrocytochrome c. That is, the data imply that the iron atom is reduced, but no obvious reductant exists to effect this change. Visible spectra and electron paramagnetic resonance studies indicate a slightly perturbed low spin Fe(III) (ferricytochrome c) species. Raman spectra for the acyl chain C-H stretching mode region show increased cardiolipin chain disorder and the involvement of the chain cis-double bond regions upon complexation. Interaction of the protein with cardiolipin changes both the porphyrin ring conformation and heme coordination to mimic the reduced cytochrome c system with no electron transfer occurring. The membrane effects of ethanol were monitored in model dipalmitoylphosphatidylcholine liposomes by spatially resolving Raman spectra across a concentration gradient. Deuterated ethanol was used as the perturbant since its unique spectral signature allows the alcohol concentration to be specified quantitatively. Both Raman spectral frequency and intensity data provided a detailed characterization of the bilayer membrane as the lipid acyl chains pass, as a function of alcohol concentration, from weakly interacting monolayers to a completely interdigitated phase.